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05 April 2013

An unbreakable bond

The strong bond between mother and calf is hard to break. In Dana Point, California, a female bottlenose dolphin (Tursiops truncatus) was seen carrying its dead calf on its back as observed by whale watchers (see March 2013 video). This behavior is also exhibited by pilot whales (Globicephala macrorhynchus/melas), and rough-toothed dolphins (Steno bredanensis) among others. [1, 2, 3] Some researchers say this is their way of mourning.
Dolphin pods exhibit this behavior within their feeding areas in the wild. [3] Mann and Watson-Capps (2005) report that mothers foraging behavior are likely during separations with their calves. Most calf mortalities happen when poor calf condition is directly affected by the maternal condition and experience during the weaning and nursing process. [4] Since observations of this behavior are often seen by whale watchers in feeding areas, it is possible that tourism may have disrupted the foraging of mothers, decreasing their maternal condition, resulting in poor calf conditions or even death. To know more about dolphins, visit SeaLifeBase.
____________________________[1] Ritter, F. (2007) Behavioural responses of rough-toothed dolphins to a dead newborn calf. Marine Mammal Science 23(2):429-433.[2] Caldwell, M.C.; Caldwell, D.K. (1966) Epimeletic (care-giving) behavior in Cetacea. Pp. 755-789 In K.S. Norris (ed) Whales, dolphins and porpoises. University of California Press, Berkeley and Los Angeles, CA.[3] Harzen, S.; Dos Santos, M.E. (1992) Three encounters with wild bottlenose dolphin (Tursiops truncatus) carrying dead calves. Aquatic Mammals 18:49-55.[4] Mann, J.; Watson-Capps, J.J. (2005) Surviving at sea: ecological and behavioural predictors of calf mortality in Indian Ocean bottlenose dolphins, Tursiops sp.Animal Behaviour 69(4):899-909.
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